Reliability in operations and maintenance –Experiences from the offshore wind sector

Niels Emsholm, Offshore manager, DONG Energy PowerÅrhus, 6th October 2009

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DONG Energy – an introduction

DONG Energy is one of the leading energy companies in Northern Europe

We are headquartered in Denmark. Our business is based on procuring,

producing, distributing and trading in energy and related products in Northern

Europe

DONG Energy has app. 5.500 employees and had a turnover of more

than DKK 60 billion in 2008

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Agenda

Offshore wind challenges

Introduction and past

Overview of offshore

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Practicalities and acces

Future

Status

Development trends

� Continous growth offshore

� Increasing cost due to offshore and oil & gas

solutions.

� Increasing cost due to lack of competition and

Dong Energy status and portfolio

� Middelgrunden (20 MW)

� Nysted Offshore Wind Farm 2003 (165 MW)

� Barrow 2007 (90 MW)

� Burbo 2008 (90 MW)

� Gunfleet Sands I+II 2009 (172 MW)� Increasing cost due to lack of competition and

still not sufficiently reliable technology

� Shortages in key areas of supply chain

� Increasing and continous focus on HSE

� Gunfleet Sands I+II 2009 (172 MW)

� Horns Rev 2 2009 (209 MW)

� Walney I + II 2010 /11(183+183 MW)

� London Array 2012 (630 MW/2)

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Why offshore wind power?

Onshore situation

� Lack of locations for onshore projects

� Lack of public acceptance of onshore

projects

Pros – offshore

� Larger energy resources

� Potentially less complicated planning

process

� Larger projects – economy of scale

Cons - offshore

� Larger investment (foundations, cables,

substations)

� More expensive O&M

DONG Energy has the vision to develop the offshore industry

2009-2015Industrializing offshore

2015-"Mega" offshore power plants

� New concepts/materials/technology

� "Supergrid"

� Ensuring technology viability

� System knowledge� Developing concepts

2000-2009Pioneering offshore

� Pipeline approach offshore windfarm installation� Embarking on scale

advantages� Sourcing

� Knowledge base� Ensuring cost efficiency gains

� Technology development� Installation and O&M

concepts

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Most offshore wind farms are being built in Northern Europe

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In the UK a large number of offshore wind farms have been constructed under the so-called Round 1 and 2 schemes

Barrow Offshore Windfarm. Operational. 50 % DE share of 90 MW.

Walney Offshore Windfarm. Approved. 100 % DE share of 600 MW.Development of Walney I with a capacity of about 150 MW. Expected commissioning of Walney I in 2011.

Westermost Rough Offshore Windfarm. Submitted. 100 % DE share of 240

Round 1 Round 2

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Shell Flats Offshore Windfarm. Submitted. 33 % DE share of about 270 MW.

Burbo Offshore Windfarm. Operational. 100 % DE share of 90 MW.

Scarweather Sands Offshore Windfarm. Approved. 50 % DE share of 90 MW.

Gunfleet Sands I Offshore Windfarm. Under construction. 100 % DE share of 108 MW.

Gunfleet Sands II Offshore Windfarm. Under construction. 100 % DE share of about 64 MW.

London Array Offshore Windfarm. Approved. 33 % DE share of 1000 MW.Development of London Array I with a capacity of about 630 MW. Expected commissioning of London Array I in 2012.

West of Duddon Sands Offshore Windfarm. Submitted. 33 % DE share of 500 MW.Expected approval of West of Duddon Sands Offshore Windfarm in spring 2008.

DE share of 240 MW.

Technological development – State of the Art

� Turbine with a rotor diameter of 120 m placed across a soccer stadium (the court is 68x105m)

� The largest commercial offshore wind turbine today has a capacity of 3.6 MW

� Focus is on increasing availability rather than size

Technological development – Key issues

Mechanical and electrical components in nacelle

and tower

Turbine access

Generator and electrical components

Platform and boat-landing

Foundation

Turbine accessGear and bearings

Growing pains!

100 m

and• Grid requirements• Siting process• Installation and commissioning process

Framework: Weather!

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Agenda

Offshore wind challenges

Introduction and past

Overview of offshore

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Practicalities and acces

Future

• Plant producing 570 GWh (consumption in 100.000 Danish households)

• Total availability high on 96,5% (excluding transformer breakdown)

• Local staffing app. 20-24 man

• Turbine type is a SWP 2,3 MW combi stall with 84 m rotor (Turbine not commercially available

anymore)

• Foundation is gravity base type of up to 2000 tonnes including ballasting

• Distance from harbour is 18 km to center

• Water depth between 6-9 m

• Weather down time app. 5%

• Substation, transformer and export cable from shore is owned , serviced and maintained by

SEAS Transmission

Nysted Offshore Wind Farm 165 MW and 72 turbines

SEAS Transmission

Introduction

• Turbine availability• Weather restrictions• Grid failure

• Historically warranties have been with turbine supplier

- Middelgrunden, Nysted, Scroby Sands and HR1

These has been amongst 1st offshore wind farms to go past warranties and have full balance of cost and income after construction

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•We have for initial wind farms scoped on MBTF to have spare parts, crew and vessels for service, minor failure and major failures

•We have started on several tracks:

- Follow up on top 10 alarms

- Reduced frequency of recommended changes or inspection in OEM manuals

- Insourcing special task (third party)

- Optimization of O&M task (DEEP or LEAN proces)

Availability is key to feasible operation

• Offshore accommodation unit

• Ensures efficient operation and maintenance work force during service periods

• accommodates 24

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Nysted Offshore Wind Farm availability 2003-2009

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• accommodates 24 persons several days/weeks

• Significantly reduces transfer time spend by the workforce

• Footbridge to the transformer station

• 3 levels

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Turbine access: More efficient operation and maintenance

• More efficient operation and

maintenance entail large potential

savings

• Up to 80 % increase in working days

if it is possible to access the turbines

in high waves

• Solutions

� Better and faster vessels

Monthly working days at different wave heights (Horns Rev II)

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28

30

25

16

25

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24

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0

5

10

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25

30

35

Jan Apr Jul Okt

2.0 m

1.5 m

1.25 m

� Better and faster vessels

� Design of boat-landings

� Helicopter service

Jan Apr Jul Okt

Reliability and cost

• A turbine in DK generates 33-46 kDKK/day

• A turbine in UK generates 80-90 kDKK/day

Opex figures are somewhat closed in the industry but 20-35 % of average revenue

stream is general expectation in the industry today on Round 1 +2 Sites

Turbine cost in O&M: 70-85 % of OPEX depending on Grid Split

5% availability is 50 mill. DKK/year for a big wind farm today10,0

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5,0

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1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930313233

Dong Energy study 2009 after expiry of SWP warranty

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Top 10 faults + availability

1. Low level of hydraulic oil 2. Generator shut-down/decoupling due to break error3. Serial connector4. Pitch tracking error5 Gear oil pressure

Different root cause analysis methods, retrofits, improved instructions and changes in parameters have reduced failures rates on these top 5 failures in 2009. This however changes availability on a wind farm like NHP with 0,3 %

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ALARMER FORDELT PÅ KOMPONENTER

Data

Komponent Antal af Aktion Sum af Varighed (timer)

Rotor 1 26

WTC Controller 5 16

Generator 3 21

Environment 1 14

Hydralic 6 19

Hovedtotal 16 96

Availability

On sea pure turbine availability of 97-98 % could be achievable

Major risks:

- Main components failure: Reduces availability with 1-3% production in life time. Many models to predict but some mostly commercial

- Cable + substation (single line, little redundancy in hardware + software)An outage can take 1-8 months depending on nature of fault, critical

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An outage can take 1-8 months depending on nature of fault, critical spare parts, weather and emergency repair plan

Weather: Many Sites have 50 % weather down time if sea access is only option

Agenda

Offshore wind challenges

Introduction and past

Overview of offshore

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Practicalities and acces

Future

Development trends in access

•Transfer is a contact sport and for vessels designed to sail fast and safe it is a challenge to combine functional requirements for accessing boat-landing and keeping steady under various wave and current conditions.

• Alternative to boat or sea transfer is still only helicopter. Due to recent helicopter accidents within the oil and gas sector with loss of life in the UK (Not similar working conditions as in wind turbines), we see no alternative other than to continue to improve access by sea, but no evident cheap and safe method has developed over the last 2-4 years except the incremental changes indicated earlier.

•In the industry the Carbon Trust amongst other have recognized the need for coordinated work for especially the UK Round 3 projects with Wind Farms over 200 km from shore/harbour and at water depths of 30-40 meters. Work between Statoil Hydro, RWE, Scottish Southern Energy and Dong Energy has

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been initiated and is to be carried out over three phases

• Company ResQ has in collaboration with Dong Energy developed an offshore yo-yo for wind turbine access structures as a primary safety device with adjusted damping coefficient.

Acces systems: Safety, Time and comfort

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Acess systems

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Design attempts for offshore transfer vessels

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Agenda

Offshore wind challenges

Introduction and past

Overview of offshore

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Practicalities and acces

Future

Future

Secondary equipment:

Lift: 4 times per year ?

Cranes:

Hooking points: UK requirements on third party inspection of hooking points and lifting equipment

under LOLER is also putting

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under LOLER is also putting

requirements.

Safety equipment (eye washer, first aid kit, emergency lowering, defibrillator) :

Pressure Vessels: Pressure vessel directive sets PV-requirements. Technicians can be trained to

perform visual inspection under

a certification regime if law requires.

HV: Requirements according to law in terms of isolation procedures . Dong Energy can in UK + DK

under stringent guidance

operate with approval systems

Future

Industry advise

•Training (not robots but intelligent staff)

• Accelerated tests (HAT)

• Simplicity in techniques but still advanced

• Simplicity in repair

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• Remote fault analysis tools

• Demo turbines are good for general design tests but not for inherent serial

failures

• Complexity kills. Many small faults will and have introduced higher CAPEX due

to large investments in boat landings, vessels, davits, helicopter access, larger

insurance premiums, more permanent staff e.t.c

Thank you for your attention

Doc. info 29

Horns Rev 1 offshore wind farm, Denmark

Challenges for O&M offshore

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DONG Energy is constructing the world's first offshore wind farm equipped with an accommodation platform

• Offshore accommodation unit

• Ensures efficient operation and maintenance work force during service periods

• accommodates 24

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• accommodates 24 persons several days/weeks

• Significantly reduces transfer time spend by the workforce

• Footbridge to the transformer station

• 3 levels